Riku isn't human. He's a rare creature called a Zaier-which looks human, but has one major difference from humans. Zaier can turn into exotic animals-well, creatures you don't normally get to see on Earth. At least, not everyday.
Another major difference Riku has from other humans, is that he lives his life being chased by the Rorard Elder-the government leader who is trying his very best to track Riku down. After all, he wants to turn Riku into his experiment. He wants to discover the true nature of the Zaier-and what makes them so special. But all Rorard can do is sit back, relax, and observe. But, without the part about relaxing. He won't relax until he has Riku in his grasp and can destroy the boy.
Riku, on the other hand, is determined to go through life keeping his head low, himself isolated, and his emotions under control-anything to keep Rorard from catching up to him. All this chase and mixture of fighting and observations is what makes Project 101.